The invention relates to implantable biocompatible vascular access port devices used in the delivery of medicines, treatments, or any other fluids into a body and/or the withdrawal of fluids from the body.
Access port devices are surgically implanted under the skin and generally include an outlet opening connected by means of a tubular conduit (catheter) system to a blood vessel within the body. Typically, such devices include septums which serve as covers for the medicine chambers and are comprised of materials which automatically reseal themselves after having been penetrated by a hypodermic needle. Fluid medications are typically infused via hypodermic needles attached to a syringe. The needle passes through the skin and through the septum into the chamber, allowing the fluid to be injected into the chamber and expelled through the catheter into the selected body site.
Conventional access port devices have either all-plastic or all-metal constructions. The plastic constructions are advantageous in that they are inexpensive to fabricate utilizing conventional molding techniques. However, plastic constructions have the disadvantage that fluids being infused into a patient sometimes react with the material and leach out unwanted or harmful compounds from the plastic material in the fluids being infused. For example, polyethersulfone is a material commonly used in such all-plastic devices. Substances found to be incompatible with polyethersulfone are acetaldehyde, aniline, benzaldehyde, chlorobenzene, chloroform, phenol, pyridine, and toluene.
Plastic constructions also have the drawback that certain compounds from the fluids sometimes adhere to the plastic reservoir surfaces, and in so doing result in an undesirable reduction or change of the potency of the fluid being delivered to the patient.
All-metal constructions significantly increase implant weight, are limited in possible design shapes, and are labor intensive to manufacture. In some cases, the metal structures are enveloped with a silastic rubber coating to improve the exterior surface and to make the device softer and more desirable for implantation and tissue contact. Such surface coatings, however, fail to address the basic shortcomings of all-metal structures and in some cases may create new hazards.
There is a need therefore for an access port device which has non-reactive metallic surfaces in contact with the fluid medications, is similar in weight to the all-plastic devices, and is easy to manufacture.
With the foregoing in mind the object of the invention is to provide a composite structure which takes advantage of the low cost, high quality construction methods available through the use of molded plastic materials, and which also takes advantage of the non-reactive characteristics of certain metallic surfaces.